Quick-connect couplings are used prevalently for connecting fuel tubes of automotive fuel systems. The quick-connect coupling is capable of simply and quickly connecting tubes without using any fastening means, such as bolts. The quick-connect coupling has a coupling body and a retainer. An end part of a tube is inserted in the coupling body, and the retainer is pressed in the coupling body to retain the tube in the coupling body. Representative techniques related with quick-connect couplings are disclosed in U.S. Pat. No. 5,542,716 and JP 2002-206683 A.
Referring to FIG. 12, an annular ridge 3 is formed on the outer circumference of an end part of a tube 2 fitted in a coupling body 4. A slide retainer 5 is pressed radially in a window formed in the coupling body 4. An end edge 6a of a rib 6 formed in the retainer engages with the annular ridge 3 to retain the end part of the tube 2 in the coupling body 4. A correct method of connecting the tube 2 and the quick-connect coupling fits the end part of the tube in the coupling body 4 first, and then the retainer 5 is pushed in the window of the coupling body 4.
However, it often occurs that the retainer 5 is pressed in the window of the coupling body 4 as shown in FIG. 13 before fitting the end part of the tube 2 in the coupling body 4. If the tube 2 is applied to the coupling body 4 in an effort to fit the end part of the tube 2 into the coupling body 4 after pressing the retainer 5 in the window of the coupling body 4, the other end edge 6b of the rib 6 stops the annular ridge 3 and obstructs the further insertion of the tube 2 in the coupling body 4.
Consequently, the quick-connect coupling and the tube 2 are connected incompletely. The appearance of the incomplete connection of the quick-connect coupling and the tube 2 cannot be discriminated from that of the complete connection of the quick-connect coupling and the tube 2. Therefore, the known quick-connect coupling is designed such that the end part of the tube 2 is unable to engage with O rings when the quick-connect coupling and the tube 2 are connected incompletely, and the incomplete connection can be found by the detection of the leakage of a fluid in a leakage test.
A quick-connect coupling disclosed in JP 11-230456 A is designed so that the incomplete connection of the quick-connect coupling and a tube can be noticed at a glance. The quick-connect coupling has, in addition to a coupling body and a retainer, complete connection verifying legs. The complete connection verifying legs cannot be easily separated from the coupling body unless the tube is inserted in the coupling body to a coupling position and the retainer is engaged normally with the tube.
Although this quick-connect coupling is capable of indicating incomplete connection, the quick-connect coupling is unable to prevent incomplete connection.